As we noted in Chapter 1, there are times when it is
necessary to kill all Oracle processes, or a selected set of
Oracle processes. You may want to kill all Oracle processes
when the database is “locked” and you cannot enter server
manager and gracefully stop the database.

When you are forced to terminate Oracle on a UNIX server,
you must perform the following steps:

1. Kill all Oracle processes associated with the ORACLE_SID
2. Use the ipcs –pmb command to identify all held RAM memory
segments, the then use the ipcrm –m command to release the
RAM memory from UNIX.
3. (non_AIX) Use the ipcs –sa command to display held
semaphores and then use the ipcrm –s command to release the
held semaphores for the instance

As we noted in Chapter 1, we can create a single command to
terminate all Oracle processes associated with your hung
database instance.